The Research Scientist Award for which this application is made will support a program of research on the causes of individual variation in use and abuse of alcohol. Informative and robust behavioral-genetic methods and analyses will be applied to extensive twin-family cohorts ascertained in Indiana and Finland. Genetic-epidemiological investigations in Finland include a five-year longitudinal study of alcohol consumption and alcohol-related attitudes, expectations, and personality dispositions in 3,200 pairs of 16 year-old twins and their families; a parallel investigation of Finnish twin children, to be initially tested at ages 8, 10, and 12, will assess genetic and familial influences on precursors of alcohol abuse in aggressive and antisocial behaviors. Adult Finnish studies will focus on patterns of alcohol consumption, personality dispositions, and related behaviors in kinships of twin parents; offspring of identical twins form genetic half-sibships socially reared as cousins in separate households, and detailed study will be made of adult offspring of twin parents who are discordant for alcohol-related disease. Laboratory twin studies in Indiana include genetic analyses of acute behavioral, cognitive, and subjective reactions to a non-intoxicating alcohol challenge among young adult twins who are classified by familial history of alcohol abuse; these studies will assess the association of candidate marker variables with familial history of alcohol abuse and analyze the repeatability and heritability of putative genetic markers at defined levels of blood alcohol content. The RSA award will permit the applicant to devote his full efforts to these research programs, to develop new research collaborations, and will provide enriched opportunities for him to acquire specialized training in structural modeling and quantitative genetic analysis to fully exploit the extensive data he is collecting. The aims of these efforts are to identify peer and familial influences, life events, and personality dispositions that underlie early initiation of high-density drinking; to evaluate genetic and familial factors in sequencing from moderate use of alcohol during adolescence/early adulthood to sustained, abusive drinking thereafter; and to assess genetic and life-history sources of the individual variation exhibited by young social drinkers in response to a nonintoxicating challenge dose of alcohol. The goal of the applicant's research program is to advance our understanding of genetic and familial-environmental pathways to alcoholism.